For background reference is made to U.S. Pat. Nos. 5,305,387, 5,208,868, 5,181,252, 4,989,271, 4,922,542, 4,644,581 and 4,455,675. Reference is also made to the Bose active noise-reducing headsets that are or were commercially available from Bose Corporation that are incorporated by reference herein.
It is an important object of the invention to provide improved noise-reducing for headsets.